This invention relates to multifilament yarns and particularly to improved multifilament polyethylene terephthalate yarns for industrial uses. More particularly, it relates to an improved multifilament polyethylene terephthalate yarn and a new fiber finishing process for polyethylene terephthalate yarns in which novel fiber finish compositions are applied to said yarns. Still more particularly, it relates to a fiber finish composition designed specifically for subsequent single dip tire cord processing for polyethylene terephthalate yarns.
Many fiber finish compositions are known. Some are quite specific in composition and relate to specific type fibers. Small changes in fiber finish composition frequently result in tremendous improvements in not only processing but also in end use of the fiber. One problem is that two chemical dip treatments are normally required for polyester tire cord in order to obtain fiber to rubber adhesion required in the use of fiber in tires.
Our U.S Pat. No. 3,730,892, issued May 1, 1973, provides a new approach to improve the dual finish system. It provides a method by which reactive adhesion promoting chemicals are applied to the yarn after the draw zone thus avoiding the critical process conditions. The method of the patent also allows the elimination of the conventional isocyanate dip in cord processing. Briefly stated, the patent discloses an improved multifilament polyethylene terephthalate yarn and process for producing said yarn, said yarn being combined with a compatible fiber finish composition of about 45 to 50 parts by weight of hexadecyl (isocetyl) stearate; about 4 to 6 parts by weight of glycerol monooleate; about 3.5 to 5.5 parts by weight of decaglycerol tetraoleate; about 5.5 to 8.1 parts by weight of polyoxyethylene tall oil fatty acid; about 8.0 to 10.0 parts by weight sulfonated glycerol trioleate; about 2.0 to 3.0 parts by weight polyoxyethylene tall oil amine; about 1.0 to 2.0 parts by weight 4,4' thiobis (6-tert-butyl-m-cresol); and about 5 to 30 parts by weight of a silane having the structural formula ##STR3## wherein n = 2 to 5.
Although the product and process of U.S. Pat. No. 3,730,892 are considered an important contribution to this art, our research in this field has continued in an effort to develop an even better process and/or product. Clearly, it would be a significant advance to find a finish consisting of only one or two components that could be used as a spin finish or as an overfinish to provide an improved tire yarn with excellent properties for use in tires.
Accordingly, a prime object of this invention is to provide an improved polyester yarn and an improved fiber finishing process for polyethylene terephthalate yarns in which novel fiber finish compositions are applied to said yarns. Other objects will be apparent from time to time in the following specification.